Question

The volume of a cylinder of height 8cm is 392π cm³. Find its lateral surface area and its total surface area.

Answer 1

Height (h) = 8cm
Let r be the radius of the cylinder.
Volume of cylinder = 392π cm³
i.e., πr²h = 392π
r² x 8 = 392
r² = 49
r = `sqrt(49)`
r = 7cm
Now, 
L.S.A. of cylinder
= 2 x π x r x h

= `2 xx (22)/(7) xx 7xx 8`
= 352cm²
T.S.A. of cylinder
= (2 x π x r x h) + (2 x π x r²)

= `(2 xx (22)/(7) xx 7 xx 8) + (2 xx (22)/(7) xx 7^2)`
= 352 + 308
= 660cm².